Automatically operated traffic control barrier

ABSTRACT

A GATE CONTROL SYSTEM INCLUDING A FIRST MAGNETIC DETECTOR 20 IN FRONT OF THE GATE RELEASES A LATCH 18 HOLDING THE GATE 14 CLOSED WHEN AN AUTOMOBILE APPROACH, AND A SECOND MAGNETIC DETECOR 22 PREVENTS OPERATION OF A HYDRAULIC PUMP MOTOR 98 FOR CLOSING THE GATE AS LONG AS AN AUTOMOBILE IS WITHIN TWO FEET. EACH MAGNETIC DETECTOR CONSISTS OF A VERTICAL MAGNETIC ROD 44 BURIED BENETAH THE ROADWAY WITH TOP AND BOTTOM COILS 46 AND 48 SUBJECTED TO AN ALTERNATING ELECTRIC FIELD TO INDUCE CURRENTS WHICH CANCEL EACH OTHER EXCEPT WHEN A AUTOMOBILE IS ABOVE THE UPPER COIL. A PROXIMITY DETETOR 26 INCLUDING AN INTENNA WIRE 124   ON THE GATE PREVENTS GATE CLOSURE IF AN OBJECT UNDER THE GATE CHANGES THE CAPACITANCE OF THE AIR GAP BETWEEN GATE AND ROADWAY.

Dec. 14, 1971 Filed April 5, 1967 C. E. RUDICEL AUTOMATICALLY OPERATED TRAFFIC CONTROL BARRIER 2 Sheets-Shoot 2 AUEgmATIC PHASE CONTROL COMPARATOR KEY OPERATED REELL DRER CIRCUIT A -C') PUMP #37 I39 P0wER I41 I: CIRCUIT LATCH 56 RELEAsE I CIRCUIT i GATE I43) I42 LATCH 2 42 v v RELEASE 5 6O PHASE RELAY & COMPARATOR ,155

E: [AUTOMATIC a GAIN CONTROL 50 5Q) 2000 cPs E152 AMPLIFIER DRWER AND FIG. 2 48 44 REFERENCE OSCILLATOR |4b I l o g |24" \P'ZS AUTOMATIC J PHASE CONTROL- PROXIMITY J L REFERENCE osc|LLAT0R 97 CIRCUIT (I29 POWER I28 L I20 2 CIRCUIT PHASE COMPARATOR I30 INVENTOR 3 OLEERAIKG CHARLES E RUDICEL CIRCUIT United States Patent 3,626,637 AUTOMATICALLY OPERATED TRAFFIC CONTROL BARRIER Charles E. Rudicel, Orlando, Fla., assignor of fractional part interest to Robert C. Knarreborg, Orlando, Fla. Filed Apr. 3, 1967. Ser. No. 627,690 Int. Cl. 1505f /20 U.S. CI. 49-25 4 Claims ABSTRACT OF THE DISCLOSURE A gate control system including a first magnetic detector in front of the gate releases a latch 18 holding the gate 14 closed when an automobile approaches, and a second magnetic detector 22 prevents operation of a hydraulic pump motor 98 for closing the gate as long as an automobile is within two feet. Each magnetic detector consists of a vertical magnetic rod 44 buried beneath the roadway with top and bottom coils 46 and 48 subjected to an alternating electric field to induce currents which cancel each other except when an automobile is above the upper coil. A proximity detector 26 including an antenna wire 124 on the gate prevents gate closure if an object under the gate changes the capacitance of the air gap between gate and roadway.

This invention relates to control of gates, particularly to vehicle parking areas, and more particularly to a system in which automatic means permit passage in one direction, but passage in the opposite direction is limited to authorized drivers who have a check, coin or key for opening the gate.

Such systems have heretofore been proposed, but known systems are subject to various disadvantages. Ultrasonic and photoelectric sensors heretofore used may get out of adjustment with the passage oftime, or under the influence of weather changes, or may be damaged by accidents or by vandals. Unauthorized parkers may attempt to thwart the control system by various means. For example, a gate might be operated by driving a vehicle up to the gate to open it then backing out so that the gate remains open and permits unauthorized cars to drive out. Sensors responsive only to automobiles have been propesd so that pedestrians or other objects cannot trigger gate operation. However, such devices might result in the gate striking a pedestrian or other object which happens to be in its closing path. Another danger with some known systems is that a gate may be locked in closed position if the power fails, or in case of other disarrangement of the system. Unauthorized or careless drivers may simply force their Way through the gates; such action may cause expensive damage to the gate arm or the operating mechanism.

Difiiculties are experienced in providing protective features overcoming the above disadvantages. For example, if a time delay switch were used to automatically close the gate a certain period of time after it was opened, the gate might close on cars which take more than the normal period of time to enter, thus damaging either the gate, its operating system, or the car.

Keeping the gate open after an authorized driver opens the gate with a check, key or coin for a long enough time for him to drive through is also a problem. Triggering of gate opening action when the car passes the sensor, which normally opens the gate for cars passing in the opposite direction, must be avoided. If a time delay override switch were used to keep the gate open, other problems might be created. Unauthorized cars might pass out closely behind the authorized cars. If the time delay is short, the gate might close either upon or in front of an authorized driver.

3,626,637 Patented Dec. 14, 1971 Among the objects of the present invention is the provision of a traific gate control system in which (1) The gate automatically opens upon failure of power so that cars may still enter and leave.

(2) The gate automatically closes when it reaches the fully open position if the automobile which triggered gate opening has left the area either by passage through the gate, or by backing away from the gate.

(3) The gate will not close, either on the car or in front of the car, if it takes a longer than normal time to pass through the gate.

(4) The gate will not close upon a person or an object under the gate even though gate opening action is normally triggered only by automobiles.

(5) The sensing devices for initiating action have no moving parts and are buried under ground where they are not subject to harm by weather, accident or tampering.

(6) The gate is designed to fail by destruction of an inexpensive shear pin without damage to expensive parts should a car force its way through the gate.

Other objects and advantages of the invention will be apparent from the following description considered in conjunction with the accompanied drawings in which:

-FIG. 1 is a schematic illustrating the gate control system of the present invention, most of the parts being shown as if viewed from the front, the associated parking lot and the gate operating sensors, however, being shown in a plan view and to a different scale;

FIG. 2, a schematic illustrating the magnetic sensors for sensing the presence of automobiles and the associated circuitry; and

FIG. 3, a schematic of the proximity sensor sensing circuitry of the invention.

Briefly stated, these and other objects are accomplished by providing as illustrated in FIG. 1 a parking gate control system which includes a parking lot 10 having a single lane entrance and exit roadway 12 blocked by a gate 14. An automobile approaching the gate is sensed by a gate opening sensor 20 located in front of the gate and triggers circuitry hereafter described to release a latch system 18 so that spring 16 opens the gate. Thereafter, as soon as a car passes beyond a gate closing sensor 22 which is buried beneath the roadway under the gate, a hydraulic motor system 24 is actuated to return the gate to blocking position. A proximity sensing system prevents closure of the gate should it approach within 4 inches of a person or an object beneath the gate.

When an authorized driver desires to remove his automobile from the lot, he initiates operation of a gate opening circuit 28 with a key, check, or coin. The gate automatically closes after he leaves.

The gate opening sensor 20 and the closing sensor 22 and their associated circuitry are substantially similar. The structure of the gate opening sensor 20 is illustrated in FIG. 2. A 3-foot length of outer diameter plastic tubing 42 containing a single 3-foot length of spiralled silicon transformer iron 44 formed of a flat ribbon tape wide and thick serves as a core although any other magnetizable core such as a cylindrical ferrite rod could be used. The cylinder is buried within the ground in a vertical position with its upper end approximately 6" below the surface. A center coil 50 of 300 turns surrounds the core. The ends of center coil 50 are connected to a 2000 c.p.s. oscillator 52. The electric field created induces a current in an upper coil 46 and a lower coil 48. Coil 46 is mounted on the plastic tube approximately 4" from one end, and has 600 turns. Coil 48 also has 600 turns and is mounted approximately 12" from the lower end. Coils 46 and 48 are connected in series-bucking relation so that the current induced in each cancels unless a large mass of metal, such as an automobile, is near the upper coil. Upper coil 46 is placed closer to the end than lower coil 48 so that it will be more highly sensitive to fast approaching metal objects. The end coils are tuned as a pair to 2000 c.p.s. to provide increased signal and phasing sensitivity and better noise rejection. The current induced in the end coils is normally approximately 90 out of phase with the signal of oscillator 52. When a vehicle approaches within 2 feet of the sensor, the output increases in amplitude and shifts in phase. The output of the end coils 46 and 48 is fed to an automobile detection circuit 54 which uses the output of the 2000 c.p.s. oscillator 52 as a reference signal. FIG. 2 shows the automobile detection circuit 54 in more detail. The end coil output is fed to a phase comparator circuit 55 through an amplifier 58 and an automatic gain control circuit 60. The phase comparator circuit 55, upon detecting the difference in phase between the end coil output and the reference signal, delivers current to a gate opening relay 56.

The automatic gain control circuit 60 maintains the amplifier sensor signal input to the phase comparator at an essentially constant level regardless of amplitude changes in the sensor output provided the output of the end coils is at the level indicative of an automobile pres ence within 2 feet of the sensor.

Gate opening relay 56 when energized opens a normally closed contact 62 to cut off current flow to a solenoid coil 64 which is part of the latch system 18. A spring 68 connects latch solenoid core 66 to latch arm 70 which is provided at its far end with a latch 71. Latch arm 70 is swingably mounted on a support 76. Latch 71 engages a latch pin 72 which is fixed to gate end 14a. The gate 14 is pivoted for movement about a shaft 75 mounted on the support 76, the gate end 14a being largely on one side of shaft 75 and the roadway blocking arm 1412 being on the other. De-energization of latch solenoid coil 64 releases the latch 71 from the latch pin 72 and permits spring 16 to rotate the gate 14 toward the vertical position.

' The hydraulic motor system 24 includes a hydraulic cylinder mounted on support 76 and having a piston 81 and a piston rod 82. The far end of piston rod 82 is pivoted to gate end 14a. Downward movement of gate arm 14a forces hydraulic fluid from the cylinder through by-pass line 84, normally open valve 85 and return line 86 to reservoir 87. Continued downward movement of gate end 14a causes downward movement of a sliding rod 90 connected to gate end 14a by means of a pivoted link 89. When gate arm 14b has raised sufficiently to clear roadway 12, the bottom 91 of sliding rod 90 engages a valve arm 92 to rotate valve 85 to closed position. This checks the rapid descent of piston 81. At approximately the same time, a stop 95 on rod 90 closes a limit switch 96 in an electric pump power circuit 97 which can (after other switches hereafter described are closed) supply power to a paralleled electric pump motor 98 and valve solenoid 100. Electric motor 98 drives a pump 102 which delivers hydraulic fluid to cylinder 80 via delivery line 103 and by-pass line 84. The coil of solenoid surrounds the magnetic core 105 of valve solenoid 100 which is connected to valve arm 92 to hold valve 85 closed whenever the pump is running.

Pump power circuit 97 includes an AC power source 107 and a normally closed switch 109 of a relay coil 110. Coil 110 is energized whenever a car is above the gate closing sensor 22 by the associated automobile detection circuti 54a. Therefore, the motor cannot run and the gate cannot close so long as a car is above closing sensor 22 and even after it passes opening sensor 20. Since sensor 22 is directly under the gate and sensor 20 is approximately one automobile length in front of the gate, it will be apparent that the latch system cannot re-engage the gate so long as a car is above sensor 20, and the gate cannot close on a car which moves forward toward sensor 22.

However, if the car backs off sensor 20, or moves for- Ward to approximately 2 feet beyond sensor 22, relay coil 110 is de-energized and the switch 109 is in its normal closed position. If limit switch 96 has been closed, or thereafter becomes closed, when the gate reaches its fully open position power is supplied to the pump motor 98 to initiate closing of the gate. By the time gate arm 14b returns to the roadblocking position, the latch solenoid coil 64 is normally energized and the latch system 18 engages and holds the arm in blocking position. Continued upward movement of piston rod 82 to a point just slightly beyond the latching position causes a projection 114 to close a limit switch 115 of the momentary close type. This energizes a relay 118 to open for several seconds a switch 119 in pump power circuit 97. This cuts off power flow to pump motor 98 and the coil of valve solenoid 100. Core 105 of the valve solenoid then returns to its normal position to move valve 85 and limit switch 96 to their normal open position. When fluid flow to cylinder 80 stops, gate opening spring 16 causes the gate to move down slightly against the latch 71 and this brings projection 114 out of engagement with limit switch 115. Switch 119 then returns to its normally closed position, and the system is again ready for operation.

However, if a pedestrian or other object gets under gate arm 14b as it swings closed, the proximity sensing system 26 energizes relay 120 causing switch 121 in pump power circuit 97 to open. This cuts ofl the pump power, and the gate swings open. The proximity system 26 includes an antenna 124 which is strung along the lower side of gate arm 14b, and which, together with the roadway ground 126 beneath the gate, serves as a capacitor 125. The capacitance of the capacitor is substantially smaller when there is a large air gap between the antenna and the ground, and is much more when a person or other object is in contact with the ground and is within 4 of the antenna. Capacitor 125 is electrically connected to a proximity sensor antenna tuned circuit 128.

The output of circuit 128 and of a 500 kc. reference oscillator tuned circuit 129 are fed to a phase comparator 130. Under normal circumstances, the output of tuned circuit 128 is approximately 90 out of phase with the signal from reference oscillator 129. Approach of the antenna to within 4" of a person or object changes the phase sufliciently to cause the output of the phase com parator to be delivered to a relay opening circuit 131 to energize a relay 120 and open a switch 121 for approximately 15 seconds. This shuts off power to the pump motor 98 for that time. At the conclusion of the 15 seconds, switch 121 closes and gate arm 14b again moves down until it approaches a disturbing object or becomes latched. Automatic phase control circuit 132 compensates for long term phase changes in the output of tuned circuit 128. Such long term shifts might be caused by such factors as changes in the humidity of the air gap between antenna 124 and the roadway. This insures that phase comparator only reacts to short term capacitance shifts such as occur when the antenna approaches within 2 feet of a person or object.

It will be seen that the proximity sensing system can delay closing of a gate, but cannot trigger gate opening.

When an authorized driver desires to leave the parking lot, he inserts a key, coin, or check in an appropriate mechanism to energize a relay coil 138 to open a switch 139 in the circuit to the latch release solenoid coil 64 so that the gate opens. As soon as switch 139 opens, it is caught by a spring-pressed latch 141 and held open. AC- cordingly, even after the driver withdraws his key, the gate cannot again latch until latch 141 is released by a solenoid coil 142. When the car passes over gate opening sensor 20, the associated phase comparator 55 feeds a pulse to a latch release circuit 143. This circuit includes obvious elements so that latch release solenoid coil 142 will become energized only after the automobile has passed over and then beyond gate opening ensor 20. Switch 139 then returns to its normal closed position, and the gate latch system 18 can lock the gate when it next closes.

Gate arm 14b is pivoted to gate end 14a by a bolt 1 34 and is held in its desired position by a shear pin 135.

If an automobile forces its way through the gate, the pin 135 is sheared and damage to other apparatus is minimized.

It will be apparent that a gate control system has been provided which automatically opens upon power failure, which automatically opens when an automobile approaches the gate, and which remains open as long as a car remains adjacent the gate and which closes immediately after the car leaves the gate. In addition, it will be apparent that the gate will not close upon a person or object under the gate, and will fail by destruction of an inexpensive shear pin if an automobile forces its way through the gate.

What is claimed is: v

1. Apparatus for controlling traflic passing over a roadway, said apparatus comprising a support located adjacent to said roadway, an elongted barrier gate swingbly mounted in a generally vertical plane intermediate its ends on said support and having one end normally disposed across the roadway, a latch bar swingably mounted on said support, said latch bar having a latch at one end selectively engageable with the other end of said gate, solenoid means connected to said latch bar for controlling the position of said latch, spring means interconnecting said support and said other end of said gate to apply a downward force to said other end of said gate and to move said one end of said gate to a roadway unblocking position when the latch is released, a first switch means located adjacent to one side of said support and electrically connected to said solenoid means to release said latch means when said first switch means is energized, fluid cylinder means mounted on said support and connected to the other end of said gate, second switch means located adjacent to said roadway on the opposite side of said gate from said first switch means, means for introducing fluid under pressure into said fluid cylinder means for returning said gate to a roadway blocking position where it will be engaged by said latch, said means for introducing fluid being controlled by said second switch means after an automobile has passed the barrier gate, so that said barrier gate normally will be held in roadway blocking position by said latch but can be moved to an unblocking position by said spring and returned to a blocking position by said fluid cylinder means.

2. The structure of claim 1 including proximity sensing means mounted on said gate for sensing the presence of an object in the path of travel of said gate while closing, and control means operated by said proximity sensing means and connected to said means for introducing fluid into said fluid cylinder means to stop the introduction of fluid and permit said spring means to return the gate to unblocking position.

3. The structure of claim 1 in which at least one of said first and second switch means includes magnetically operated sensing means located along the roadway for sensing the presence of an automobile and automatically releasing said latch.

4. The structure of claim 1 including a manually operated switch means located along the roadway on at least one side of said gate for releasing said latch.

References Cited UNITED STATES PATENTS 2,201,146 5/1940 Barker 34038 L 2,687,588 8/1954 Nutter 49--31 1,899,496 2/1933 Day 246-127 X 2,899,545 8/ 1959 Fernandez 246127 3,046,522 7/1962 Aver, Jr. 34051 3,233,234 2/1966 Stelrnach 340258 C 3,249,915 5/1966 Koerner 348--35 L 3,341,813 9/1967 Fletcher et al. 34038 3,373,374 3/1968 Marosi 34038 L 2,963,627 12/1960 Buchsbaum 340258 C X 3,237,105 2/1966 Kalrnas 340258 C 3,406,802 10/1968 Needham et al 3285 X FOREIGN PATENTS 647,964 9/ 1962 Canada 340258 JAMES W. LAWRENCE, Primary Examiner D. C. NELMS, Assistant Examiner US. Cl. X.R. 

